The present invention relates to a light source apparatus for an endoscope that makes an exciting light for fluorescence excitation incident upon a light guide in an endoscope.
An organism tissue is excited and generates fluorescence when irradiated with a light of a specific wavelength. An abnormal organism tissue suffering a lesion such as a tumor or cancer generates weaker fluorescence than a normal organism tissue. Such reaction is also seen in an organism tissue under a body cavity wall. Recently, endoscope systems that detect a lesion that has emerged in an organism tissue under a body cavity wall based on such reaction have been developed.
One of such endoscope systems is designed to perform a normal observation mode of emitting an illuminating light of a visible wavelength range from a tip portion of the endoscope to illuminate inside of the body cavity and shooting an image formed by the illuminating light reflected by a surface of the body cavity wall with an imaging apparatus, as well as a fluorescence observation mode of emitting a light of a specific wavelength range from the tip portion of the endoscope for exciting the organism tissue, and shooting an image formed by the fluorescence generated by the organism tissue excited by such light under the body cavity, with the imaging apparatus.
A light source apparatus employed in the endoscope system described above includes therein a visible light source and an exciting light source, and an optical path merging device such as a dichroic mirror that merges an optical path of the illuminating light emitted by the visible light source and that of the exciting light emitted by the exciting light source. The light source apparatus provides to a light guide fiber bundle of the endoscope connected to the light source apparatus, the illuminating light emitted by the visible light source in the normal observation mode, and the exciting light emitted by the exciting light source in the fluorescence observation mode.
Conventionally a mercury vapor lamp or a xenon lamp has been employed as the light source of the exciting light. The mercury vapor lamp, however, cannot be instantaneously turned on and off, which disturbs quick switching with the illuminating light, and besides turns into a hazardous waste when disposed. Also, the visible light emitted by the xenon lamp is not capable of sufficiently exciting the organism tissue, and hence a photomultiplier tube has to be employed for capturing the dim fluorescence, which makes the imaging apparatus more complicated.
Accordingly, the light source apparatus for an endoscope lately developed employs, as disclosed in U.S. Pat. No. 6,468,204, for example, an UV-emitting type semiconductor laser as the exciting light source. Employing such semiconductor laser allows instantaneously turning on and off, and also creating the fluorescence having sufficient intensity.
When employing the laser light source as the exciting light source, however, a certain preparation period (approx. three minutes in case of the semiconductor laser) is required before the laser beam becomes ready to be stably output, upon turning on the power for the light source apparatus to activate the laser light source by cold boot. Therefore the operator has to take the trouble to press the turn-on button several times, before the laser beam is stably output.
In view of the foregoing problems incidental to the conventional art, aspects of the invention is advantageous in that, there is provided a light source apparatus for an endoscope capable of quickly starting to stably output an exciting light without the need to repeatedly press the turn-on button after turning on the power, even when a laser light source is employed as the exciting light source.
Aspects of the invention provided a light source apparatus for an endoscope, designed to make an exciting light that excites an organism tissue to thereby induce fluorescence incident upon a light guide disposed through a portion of the endoscope to be inserted into a body cavity, comprising an exciting laser light source that emits the exciting light; a monitor sensor that monitors an output of the exciting laser light source and outputs a turn-on enable signal when the exciting laser light source is ready to stably emit a beam; an indicator that indicates whether the exciting laser light source is ready for immediate emission; a shutter mechanism that opens and closes an optical path of the exciting light; an optical system that makes the exciting light that has passed the shutter mechanism incident upon a proximal facet of the light guide; and a controller that controls the exciting laser light source. The controller intermittently turns on the exciting laser light source for testing and controls the shutter mechanism so as to close the optical path of the exciting light, during a period after laser irradiation is permitted until the monitor sensor outputs the turn-on enable signal; controls the shutter mechanism so as to open the optical path of the exciting light and controls the indicator so as to indicate to the effect that the exciting laser light source is ready for immediate emission, when the monitor sensor outputs the turn-on enable signal; and turns on the exciting laser light source when an exciting light turn-on signal is input, thereby making the exciting light incident upon the light guide.
It is preferable that the controller controls the indicator, after the laser irradiation is permitted and before the monitor sensor outputs the turn-on enable signal so as to indicate to the effect that the exciting laser light source is in a preparation phase for emission.